Oral cancer is the sixth common malignancy and is a major cause of cancer morbidity and mortality worldwide. Globally about 500,000 new oral and pharyngeal cancers are diagnosed annually, and three quarters of these are from the developing world (Gupta P C. 1982 “Comparison of carcinogenecity of betal quid with and without tobacco: an epidemiologic review.” Ecology of Disease 1: 213-219; Saranath. 2000 “Integrated Biology and Molecular pathology of oral cancer. Contemporary issue in oral cancer.” Oxford university press: 30-71). In India, at the Tata Memorial Hospital (Dinshaw and Ganesh. 2005 Hospital Based Cancer Registry, Annual report 2001, Tata Memorial Hospital.) cancers of the head and neck comprise of ˜25% of cancers presenting in male with cancers of the oral cavity constituting ˜12% of the total cancer load and 52% of the head and neck cases. Of these, cancers of the gingivo-buccal complex and those of the tongue are ˜59% and ˜21% respectively of the oral cavity. Most of the gingivo-buccal complex cancers present at stage III and W.
At present the major modality for treatment of these cancers is surgery for stage III and IV cancers, followed by radiotherapy. Early stage cancers are often treated with surgery or radiotherapy alone. The five-year survival is very low and about 60% return with a recurrence or local nodal metastasis.
Major problem is that the choice of therapy for each patient is based on interpretation of clinical and histopathological observations in light of previous clinical experience. However, disease that is clinically similar can behave differently due to diverse combinations of molecular alterations determining disease prognosis. Use of molecular markers to help in prognostication of oral cancer is thus necessary.
Autoantibodies to qualitatively or quantitatively modified cellular proteins are known to be produced by patients in certain diseases such as autoimmune diseases and cardiovascular-related disorders, in some cases even before the onset of the disease. There is increasing evidence for an immune response to cancer in humans, as demonstrated in part by the identification of auto antibodies against a number of intracellular and surface antigens detectable in sera from patients with different cancer types (Le Naour. 2001 “contribution of proteomics to tumor immunology.” Proteomics 1: 1295-302; Hanash. 2003 “Harnessing immunity for cancer marker discovery.” Nat Biotechnol 21: 37-8; Yang and Yang. 2005 “New concepts in tumor antigens: Their significance in future immunotherapies for tumors.” Cellular and Molecular Immunology 2: 331-341; Anderson and LaBaer. 2005 “The sentinel within: exploiting the immune system for cancer biomarkers.” J Proteome Res 4: 1123-33). The detection of autoantibodies to cellular antigens and the identification of proteins that have elicited autoantibodies have been accomplished using a variety of approaches. Early studies involving the immune system investigated the circulating immune complexes to identify antigen-antibody complexes in circulation (Carpentier et al. 1982 “Circulating immune complexes and the prognosis of acute myeloid leukemia.” N Engl J Med 307: 1174-80.) This was followed by SEREX analysis wherein a cDNA expression library from tumor tissue is screened with autologous/heterologous sera (Sahin et al. 1995 “Human neoplasms elicit multiple specific immune responses in the autologous host.” Proc Natl Acad Sci USA 92: 11810-3; Old and Chen. 1998 “New paths in human cancer serology.” J Exp Med 187: 1163-7). A recent modified approach involves the screening of a random peptide library with patient's sera (Mintz et al. 2003 “Fingerprinting the circulating repertoire of antibodies from cancer patients.” Nat Biotechnol 21: 57-63). Several studies have identified autoimmunity against single different proteins such as p53, hsp 90, c-erbB-2/HER2/neu and mucin-related antigens in breast cancer (Lenner et al. 1999 “Serum antibodies against p53 in relation to cancer risk and prognosis in breast cancer: a population-based epidemiological study.” Br J Cancer 79: 927-32; Conroy et al. 1998 “Autoantibodies to the 90 kDa heat shock protein and poor survival in breast cancer patients.” Eur J Cancer 34: 942-3; Disis et al. 1997. “High-titer HER-2/neu protein-specific antibody can be detected in patients with early stage breast cancer.” J Clin Oncol 15: 3363-3367; von Mensdorff-Pouilly et al. 1996 “Humoral immune response to polymorphic epithelial mucin (MUC-1) in patients with benign and malignant breast tumours.” Eur J Cancer 32A: 1325-31). These studies have shown the presence of autoantibodies in variable amounts ranging from 10%-20% suggesting that several different factors that contribute to humoral response in individuals. A related study which has addressed the presence of p53 antigen and its antibody in different cancers (Soussi. 2000 “p53 Antibodies in the sera of patients with various types of cancer: a review.” Cancer Res 60: 1777-88). and also in head and neck tumors (Soussi. 2000 “p53 Antibodies in the sera of patients with various types of cancer: a review.” Cancer Res 60: 1777-88; Ralhan et al. 1998 “Circulating p53 antibodies as early markers of oral cancer: correlation with p53 alterations.” Clin Cancer Res 4: 2147-52), shows, that p53 antibodies are associated with high grade tumors and poor survival. Several recent investigations have used the 2D proteomics approaches coupled with immunostaining with auto/heterologous sera to identify tumor antigens eliciting an immune response. Some of the antigens are β-tubulin, SM 22-α/CAI, annexin I and II, PGP9.5, RS/DJ I, MUC I, CK8, alpha enolase, aldehyde dehydrogenase, peroxiredoxin VI, and triose phosphate isomerase in different cancers and healthy individuals, (Le Naour. 2001 “Contribution of proteomics to tumor immunology.” Proteomics 1: 1295-302; Prasannani et al. 2000 “Identification of beta-tubulin isoforms as tumor antigens in neuroblastoma.” Clin Cancer Res 6: 3949-56; Brichory et al. 2001 “Proteomics-based identification of protein gene product 9.5 as a tumor antigen that induces a humoral immune response in lung cancer.” Cancer Res 61: 7908-12; Klade et al. 2001 “Identification of tumor antigens in renal cell carcinoma by serological proteome analysis.” Proteomics 1: 890-8; Brichory et al. 2001 “An immune response manifested by the common occurrence of annexins I and II autoantibodies and high circulating levels of IL-6 in lung cancer.” Proc Natl Acad Sci USA 98: 9824-9; H. Yuichiro et al. 2003 “Circulating anti-MUC1 IgG antibodies as a favorable prognostic factor for pancreatic cancer.” Int. J Cancer 103: 97-100; Gires et al. 2004 “Profile identification of disease-associated humoral antigens using AMIDA, a novel proteomics-based technology.” Cell Mol Life Sci 61: 1198-207; Naour et al. 2002 “A distinct repertoire of autoantibodies in hepatocellular carcinoma identified by proteomic analysis.” Mol Cell Proteomics 1: 197-203; Nakanishi et al. 2006 “Detection of eight antibodies in cancer patients' sera against proteins derived from the adenocarcinoma A549 cell line using proteomics-based analysis.” J Chromatogr B Analyt Technol Biomed Life Sci; Li et al. 2006 “Proteomics-based identification of autoantibodies in the sera of healthy Chinese individuals from Beijing.” Proteomics 6: 4781-9; Fujita et al. 2006 “Proteomics-based approach identifying autoantibody against peroxiredoxin VI as a novel serum marker in esophageal squamous cell carcinoma.” Clin Cancer Res 12: 6415-20). However global autoantibody response has not been evaluated in cancers of gingivo-buccal complex. Identification of tumor antigens or their corresponding antibodies in serum have utility as indicators of risk for particular types of cancer or as diagnostic markers or as prognostic indicators.
It is becoming apparent that although some of the tumor antigens are expressed on the tumor cell surface, most of the tumor antigens identified so far are intracellular proteins (Yang and Yang. 2005 “New concepts in tumor antigens: Their significance in future immunotherapies for tumors.” Cellular and Molecular Immunology 2: 331-341; Anderson and LaBaer. 2005 “The sentinel within: exploiting the immune system for cancer biomarkers.” J Proteome Res 4: 1123-33). Some of the intracellular molecules such as cytokeratin 8 (Gires et al. 2005 “Cytokeratin 8 associates with the external leaflet of plasma membranes in tumour cells.” Biochem Biophys Res Commun 328: 1154-62), enolase (Moscato et al. 2000 “Surface expression of a glycolytic enzyme, alpha-enolase, recognized by autoantibodies in connective tissue disorders.” Eur J Immunol 30: 3575-84) and β actin (Wang et al. 2004 “Cell surface-dependent generation of angiostatin4.5.” Cancer Res 64: 162-8) relocate to the cell membrane in cancer. In summary immune responses arise due to tumor specific alterations in protein expression, mutation, folding, degradation, intracellular localization (Anderson and LaBaer. 2005 “The sentinel within: exploiting the immune system for cancer biomarkers.” J Proteome Res 4: 1123-33; Gires et al. 2005 “Cytokeratin 8 associates with the external leaflet of plasma membranes in tumour cells.” Biochem Biophys Res Commun 328: 1154-62; Yang and Yang. 2005 “New concepts in tumor antigens: Their significance in future immunotherapies for tumors.” Cellular and Molecular Immunology 2: 331-341) and their exposure to immune system following necrosis. Response to most tumor antigens is rarely observed in healthy individuals. Antibody immune responses therefore show promise as clinical biomarkers because antibodies have long half life in serum, are easy to measure and are relatively stable in blood samples' (Anderson and LaBaer. 2005 “The sentinel within: exploiting the immune system for cancer biomarkers.” J Proteome Res 4: 1123-33; Gires et al. 2005 “Cytokeratin 8 associates with the external leaflet of plasma membranes in tumour cells.” Biochem Biophys Res Commun 328: 1154-62; Robinson et al. 2002 “Autoantigen microarrays for multiplex characterization of autoantibody responses.” Nat Med 8: 295-301; Yang and Yang. 2005 “New concepts in tumor antigens: Their significance in future immunotherapies for tumors.” Cellular and Molecular Immunology 2: 331-341). Autoantigen microarray can be developed for multiplex characterization of autoantibody response. (Robinson et al. 2002 “Autoantigen microarrays for multiplex characterization of autoantibody responses.” Nat Med 8: 295-301). It is reported in literature that no single marker is adequate for the detection and prognosis and several antigens would be required for high sensitivity and specificity (Yang and Yang. 2005 “New concepts in tumor antigens: Their significance in future immunotherapies for tumors.” Cellular and Molecular Immunology 2: 331-341).